Lipid composition of brain myelin from normal and hyperphenylalaninemic chick embryos

The influence of hyperphenylalaninemia on the lipid composition of brain myelin has been investigated in 19-day-old chick embryos. CNP-ase activity was used as myelin marker enzyme for myelin isolation. CNP-ase activity was significantly lower in hyperphenylalaninemic myelin when compared with control. No significant differences were observed after experimental treatment in the total lipid content of myelin as well as in the proportion of cholesterol:phospholipid:galactolipid. Nevertheless, a clear increase in the percentage of esterified cholesterol was found. No appreciable alterations were observed in the phospholipid composition of brain myelin from both control and hyperphenylalaninemic chick embryos. However, the ratio of unsaturated to saturated fatty acids in serine plasmalogen and sphingomyelin was considerably increased by this treatment. This ratio in choline and ethanolamine phosphatides from treated embryos did not differ from that of controls.     

Architecture of the T-system in helical paramyosin muscles of an annelid (Branchiobdella)

Tannic acid impregnation has revealed the existence of a T-system in the helical fibers of Branchiobdella pentodonta (Annelida, Clitellata). T-tubules are L-shaped inside the fiber, within the plane of the I-band: after a short horizontal tract they run longitudinally for a long tract keeping contact with many sarcoplasmic reticulum cisternae and forming dyads. The presence of a T-system in this annelid, the only one demonstrated up to now in annelids, is to be ascribed to the thickness of the contractile layer of those fibers.     

Helicotylenchus oleae n. sp. and H. neopaxilli n. sp. (Hoplolaimidae), Two New Spiral Nematodes Parasitic on Olive Trees in Italy

Helicotylenchus oleae n. sp. and H. neopaxilli n. sp., from olive roots and soil in Italy, are described and illustrated. Helicotylenchus oleae can be distinguished from the related species H. canadensis and H. tunisiensis especially by the smaller styler, its distinctive tail shape, and a tail longer than one anal body width. Helicotylenchus neopaxilli differs from the close species H. paxilli by having a conical, anteriorly truncated labial region, shorter stylet, and phasmids always anterior to level of anus. Also illustrated and discussed are histopathological changes within feeder roots of olive caused by the feeding activity of the semi-endoparasitic H. oleae.     

1H NMR studies at 360 Mhz of the methyl groups in native and chemically modified basic pancreatic trypsin inhibitor (BPTI)

In the ¹H NMR spectra obtained at 360 MHz after digital resolution enhancement, the multiplet resonances of the methyl groups in the basic pancreatic trypsin inhibitor (BPTI) were resolved. With suitable double irradiation techniques the individual methyl resonances were assigned to the different types of aliphatic amino acid residues. Furthermore, from pH titration and comparison of the native protein with chemically modified BPTI, the resonance lines of Ala 16 in the active site and Ala 58 at the C-terminus were identified. Potential applications of the resolved methyl resonances as natural NMR probes for studies of the molecular conformations are discussed.     

Enkephalin-binding systems in human plasma

Three amino acid-containing fractions present in human plasma are shown to bind both leu and met-enkephalin: serum albumin and two species of a much lower molecular weight, in all likelihood polypeptides. The amount of enkephalin associated with serum albumin seems comparatively smaller than that associated with the two low molecular weight systems. These systems jointly are apparently capable of binding a significant part of the circulating enkephalins. The possibility is suggested that the interactions described may play a role in maintaining the integrity of circulating enkephalins.     

Erratum

A specific copper chelator, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonic acid substituted for mercaptoethanol to support growth of a L1210 lymphoma in primary culture. Added Cu⁺⁺, but not Zn⁺⁺ or Fe⁺⁺ interfered with growth promotion by the chelator. It also can protect an established L1210 culture, which does not require mercaptoethanol, from cytotoxicity of two bis-thiosemicarbazones. Since these are known to require copper for cytotoxicity, the results indicate that 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonic acid acts by removing a source of endogenous copper in the tissue culture medium which prevents growth of the primary culture.     

Molecular cloning of pea mRNAs encoding a shoot-specific polypeptide and light-induced polypeptides

Summary The molecular cloning of cDNA corresponds to pea seedling mRNA sequences encoding a shoot-specific polypeptide, the small subunit of the ribulose 1,5 biphosphate carboxylase and a component of the light-harvesting chlorophyll a/b complex is described. cDNA prepared from polysomal poly(A)RNA of light-grown shoots was enriched for shoot-specific and light-induced sequences by heterologous liquid hybridization with mercurated polysomal poly(A)RNA of dark-grown roots, followed by sulfhydryl chromatography. Cloned shoot-specific sequences were identified by 2D electrophoretic analysis of hybrid release translation products. The cloned shoot-specific sequence corresponded to a mRNA of 850 nt present both in light-and dark-grown shoots, and produced anin vitro translation product of M_r27 500 and isoelectric point of 4.7.     

Cytotoxic effect of adriamycin and agarose-coupled adriamycin on glomerular epithelial cells: Role of free radicals

Summary It has been suggested that the generation of toxic radicals plays an important role in toxicity by Adriamycin (ADR) on cancer cell lines and in vivo. We have examined the role of free radicals in determining toxicity and resistance to ADR of rat glomerular epithelial cells in culture; this method provides a good model for analyzing the mechanisms responsible for ADR experimental nephrosis in rats. Three points were established: a) the intra- or extracellular site of ADR toxicity; b) the role of the superoxide anion and of the hydroxyl radical in determining intra- and-extracellular cytotoxicity; and c) the implication of oxido-reduction cycling as a potential route for ADR semiquinone transformation. Free ADR was found to induce the same inhibition of [³H]thymidine incorporation into DNA as ADR bound to an agarose macroporous bed which prevents the intracellular incorporation of the drug. Specific scavenging of free radical activity by the enzymes catalase and superoxide dismutase, the hydroxyl radical inhibitors dimethyl sulfoxide and dimethylthiourea (DMTU) and by chelation of intracellular free iron with deferoxamine produced only a partial restoration of [³H]thymidine incorporation into DNA, which was maximal for DMTU (30% of normal incorporation). DMTU treatment was unsuccessful in preventing the extracellular cytostatic effect of ADR. Finally, glomerular epithelial cell killing (⁵¹Cr-release method) by 5-iminodaunorubicin, an ADR analogue with a modified quinone function that prohibits oxido-reduction cycling, was higher than unmodified ADR. These results indicate that ADR may exert its cytotoxic effects on glomerular epithelial cells by interaction at the cell surface, whereas the intracellular compartment, principally DNA, does not seem to be the target of ADR effects. They also suggest that the free radicals are in part responsible for ADR intracellular cytotoxicity, but other mechanisms should also be hypothesized. Finally, the participation of the ADR semiquinone radical in oxido-reduction cycling seems not important for the induction of the cellular damage.     

Pasteuria sp. Parasitizing Trophonema okamotoi in Florida

Two populations of Trophonema okamotoi parasitized by Pasteuria sp. were found on Liquidambar styraciflua (sweetgum) and on an unidentified tropical grass in north-central Florida. Endospores of this Pasteuria sp. attached to motile vermiform second-stage juveniles (J2) and males of T. okamotoi, but not to other developmental stages. Sporangia and new endospores were produced only inside the bodies of swollen and sedentary third- and fourth-stage juveniles and females that developed in the host roots. No egg masses were produced by infected T. okamotoi females. The endospore diameter from the tropical grass population was 4.93 μm and the central core diameter was 1.97 μm; measurements of endospores from the sweetgum populations were similar. Endospores that were collected from T. okamotoi and added to uninfected T. okamotoi and other plant-parasitic nematodes attached/to J2 of T. okamotoi but did not attach to juveniles and adults of Helicotylenchus pseudorotrustus, Pratylenchus brachyurus, or to J2 of either Meloidogyne arenaria race 1, M. incognita race 1, M. javanica, or Tylenchulus semipenetrans. Pasteuria sp. from T. okamotoi differed from the described Pasteuria species in endospore size, host preference, and rate of attachment.